chore(scripts): generic way to build scripts (#829)

* chore: move core scripts

* chore: extract head scripts

assets/js/core/theme.js

@@ -0,0 +1,61 @@
+// Light / Dark theme toggle
+(function () {
+  const defaultTheme = '{{ site.Params.theme.default | default `system`}}'
+  const themes = ["light", "dark"];
+
+  const themeToggleButtons = document.querySelectorAll(".hextra-theme-toggle");
+  const themeToggleOptions = document.querySelectorAll(".hextra-theme-toggle-options p");
+
+  function applyTheme(theme) {
+    theme = themes.includes(theme) ? theme : "system";
+
+    themeToggleButtons.forEach((btn) => btn.parentElement.dataset.theme = theme );
+
+    localStorage.setItem("color-theme", theme);
+  }
+
+  function switchTheme(theme) {
+    setTheme(theme);
+    applyTheme(theme);
+  }
+
+  const colorTheme = "color-theme" in localStorage ? localStorage.getItem("color-theme") : defaultTheme;
+  switchTheme(colorTheme);
+
+  // Add click event handler to the menu items.
+  themeToggleOptions.forEach((option) => {
+    option.addEventListener("click", function (e) {
+      e.preventDefault();
+
+      switchTheme(option.dataset.item);
+    })
+  })
+
+  // Add click event handler to the buttons
+  themeToggleButtons.forEach((toggler) => {
+    toggler.addEventListener("click", function (e) {
+      e.preventDefault();
+
+      toggleMenu(toggler);
+    });
+  });
+
+  window.addEventListener("resize", () => themeToggleButtons.forEach(resizeMenu))
+
+  // Dismiss the menu when clicking outside
+  document.addEventListener('click', (e) => {
+    if (e.target.closest('.hextra-theme-toggle') === null) {
+      themeToggleButtons.forEach((toggler) => {
+        toggler.dataset.state = 'closed';
+        toggler.nextElementSibling.classList.add('hx:hidden');
+      });
+    }
+  });
+
+  // Listen for system theme changes
+  window.matchMedia("(prefers-color-scheme: dark)").addEventListener("change", () => {
+    if (localStorage.getItem("color-theme") === "system") {
+      setTheme("system");
+    }
+  });
+})();